System and method for transferring navigation information using different coordinate systems

ABSTRACT

A system and method for formatting and transferring navigation information is disclosed. The system and method can send and receive navigation information. The navigation information can be formatted and transferred using different coordinate systems. In some cases, an absolute coordinate system is used and in other cases, a relative coordinate system is used to encode or express various map features. This can assist in reducing the amount of information transferred and can facilitate rapid delivery of the navigation information.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/531,664, filed on Dec. 23, 2003. This ProvisionalPatent Application is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field of the Invention

This invention relates to the field of navigation, and moreparticularly, to a system and method for managing navigationinformation.

2. Related Art

Currently, some motor vehicles include provisions for providingnavigation information and driving directions to the driver. Thesenavigation systems generally comprise a system that is built into amotor vehicle. These systems are usually designed so that, after leavingthe factory, the systems are self-contained units. And all of thenavigation information that is available to direct a driver to aparticular destination is contained within the system.

All of this information usually requires considerable computer resourcesto store, search and manage all of the data. Large storage capacity,fast processors, large amounts of memory and other costly computerequipment are all required to manage and process all of the navigationequipment.

While this arrangement does provide navigation assistance, there are anumber of drawbacks. First, current systems are expensive. In manycases, current navigation systems can significantly increase the cost ofpurchasing a motor vehicle. Also, updating the system is cumbersome andexpensive.

Some systems are incapable of receiving updates. For systems, all of thenavigation information initially programmed is all that is everavailable. These systems cannot assist users in finding a destinationthat is located on a new street or new development. Some systems areupdated by installing or replacing a new storage medium. In some cases,a high capacity storage medium like an optical disk, for example a CD orDVD-ROM, is inserted. In some other cases, a new optical disk containingupdates replaces the existing optical disk. While these systems arecapable of receiving updates, providing these new optical disks isexpensive and cumbersome. The proprietor must produce and create a newoptical disk with the updated information and distribute the opticaldisk. Users must purchase or obtain the disk and install the updatedinformation. Because of the cost and inconvenience associated with thisprocess, updates practical are only about once a year.

There is currently a need for a system that is less expensive and can beeasily updated. There is also a need for a system that can delivernavigation information using existing infrastructure and can delivernavigation information in real time.

SUMMARY

A system and method for managing navigation information are disclosed.The invention can be used in connection with a motor vehicle. The term“motor vehicle” as used throughout the specification and claims refersto any moving vehicle that is capable of carrying one or more humanoccupants and is powered by any form of energy. The term motor vehicleincludes, but is not limited to cars, trucks, vans, minivans, SUV's,motorcycles, scooters, boats, personal watercraft, and aircraft.

The system and method can send and receive navigation information. Insome cases, requests for navigation information can be sent to a serviceprovider, which then prepares an appropriate response and sends theresponse back to the requesting party. Various techniques can be used tofacilitate rapid and real time delivery of the navigation information tothe requesting party.

In one aspect, the invention provides an on-board unit for receivingnavigation information comprising a GPS antenna port configured toreceive information from a GPS antenna, a wireless communications portconfigured to receive information from a wireless network, and a displayport configured to communicate with a display device, where the on-boardunit receives navigation information through the wireless communicationsport; and where the navigation information includes data formatted inrelative coordinates and data formatted in absolute coordinates.

In another aspect, the invention provides a method for preparingnavigation information comprising the following steps: receiving arequest for navigation information, determining an overall route andconstructing an overall map, selecting a first portion of the overallmap, and determining whether the first portion is more efficientlyencoded using relative or absolute coordinates.

In another aspect, the invention provides a method for preparingnavigation information comprising the following steps: receiving arequest for the navigation information, preparing the navigationinformation using an absolute coordinate system and a relativecoordinate system, where the absolute system uses two bytes to defineeach absolute coordinate, and where the relative coordinate system usestwo bytes to define an initial coordinate and uses one byte to define asubsequent coordinate.

In another aspect, one byte includes a first half comprising half of thebits of the one byte and a second half of bits comprising the other halfof bits of the one byte, where the first half of bits is used to definea value for displacement in a first direction and the second half ofbits is used to define a value for displacement in a second direction.

In another aspect, the invention provides a method for preparingnavigation information comprising the following steps: receiving arequest for navigation information, gathering information related to aroute between a starting point and a destination point, establishing afirst region having a first level of detail, establishing a secondregion having a second level of detail, and where the first level ofdetail is different than the second level of detail.

In another aspect, the invention provides a method for preparingnavigation information comprising the following steps: receiving arequest for navigation information, gathering information related to aroute between a starting point and a destination point, establishing aroute first region associated with the route, having a first level ofdetail, and having a portion extending a first distance from the route,establishing an end point first region associated with an end point,having the first level of detail, and extending a second distance fromthe end point, and where the first distance is less than the seconddistance.

In another aspect, the invention provides a method for sendingnavigation information comprising the following steps: gatheringinformation related to a route between a starting point and adestination point, gathering detailed information related to thestarting point, gathering detailed information related to thedestination point, gathering detailed information related to the route,and sending the information related to the route between the startingpoint and the destination point before any other information is sent.

In another aspect, the invention provides an on-board unit for receivingnavigation information. The on-board unit can include a GPS antenna portconfigured to receive information from a GPS antenna, a wirelesscommunications port configured to receive information from a wirelessnetwork and a display port configured to communicate with a displaydevice. The on-board unit receives navigation information through thewireless communications port. The navigation information includes dataformatted in relative coordinates and data formatted in absolutecoordinates.

In another aspect, the navigation information includes first map regionsencoded in relative coordinates and second map regions encoded inabsolute coordinates.

In another aspect, the navigation information includes first mapfeatures encoded in relative coordinates and second map features encodedin absolute coordinates. These map features can be roads, bodies ofwater or any other map feature.

In another aspect, the first map feature is the same kind of map featureas the second map feature.

In another aspect, the navigation information includes a map feature,where a first portion of the map feature is encoded in relativecoordinates and second portion of the map feature is encoded in absolutecoordinates.

In another aspect, the navigation information includes a map feature,wherein a first axis of the map feature is encoded in relativecoordinates and second axis of the map feature is encoded in absolutecoordinates.

In another aspect, the invention provides a method for preparingnavigation information. This method can include the following steps:receiving a request for navigation information, determining an overallroute and constructing an overall map, selecting a first portion of theoverall map; and determining whether the first portion is moreefficiently encoded using relative or absolute coordinates.

In another aspect, the first portion is encoded using relativecoordinates.

In another aspect, the method provides a step of selecting a secondportion of the overall map and encoding the second portion usingabsolute coordinates.

In another aspect, the method provides a step of determining if theoverall map has been completely encoded.

In another aspect, the method provides a step of assembling the overallmap using the first map portion and second map portion. These mapportions can be a geographical region or a map feature.

In another aspect, the first map portion is a first axis of a mapfeature and the second map portion is a second axis of the map feature.

In another aspect, the invention provides a method for preparingnavigation information that includes the following steps: receiving arequest for the navigation information, preparing the navigationinformation using an absolute coordinate system and a relativecoordinate system, where the absolute coordinate system uses two bytesto define each absolute coordinate; and where the relative coordinatesystem uses two bytes to define an initial coordinate and uses one byteto define a subsequent coordinate.

In another aspect, the subsequent coordinate is defined by adisplacement from the initial coordinate.

In another aspect, the one byte used to define the subsequent coordinateincludes a value for displacement in a first direction.

In another aspect, the one byte used to define the subsequent coordinateincludes a value for displacement in a second direction.

In another aspect, the one byte includes a value for displacement in afirst direction and a second direction. In some cases, the firstdirection is in a direction of an X-axis and wherein the seconddirection is in a direction of a Y-axis.

In another aspect, a first portion of bits of the one byte are used todefine a value for displacement in a first direction.

In another aspect, a second portion of bits of the one byte are used todefine a value for displacement in a second direction.

In another aspect, the one byte includes a first half comprising half ofthe bits of the one byte and a second half of bits comprising the otherhalf of bits of the one byte; wherein the first half of bits is used todefine a value for displacement in a first direction and the second halfof bits is used to define a value for displacement in a seconddirection.

Other systems, methods, features and advantages of the invention willbe, or will become, apparent to one with skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description, be within the scope ofthe invention, and be protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is a schematic diagram of a preferred embodiment of a vehicle inassociation with a wireless communication system and a service provider.

FIG. 2 is a schematic diagram of a preferred embodiment of a serviceprovider in association with an update resource and a billing system.

FIG. 3 is a schematic diagram of a preferred embodiment of a centralunit and associated components.

FIG. 4 is a schematic diagram of the interior of the vehicle shown inFIG. 1.

FIG. 5 is a flow diagram of a preferred embodiment of a method forrequesting and receiving navigation information.

FIG. 6 is a flow diagram of a preferred embodiment of a method forassembling a map.

FIG. 7 is a schematic diagram of a preferred embodiment of a map withregions.

FIG. 8 is a schematic diagram of a preferred embodiment of a map withmap features.

FIG. 9 is a schematic diagram of a preferred embodiment of a map withmap features.

FIG. 10 is a schematic diagram of a preferred embodiment of an examplemap.

FIG. 11 is a schematic diagram of a preferred embodiment of an examplemap with an example route.

FIG. 12 is a schematic diagram of a preferred embodiment of mapinformation.

FIG. 13 is a schematic diagram of a preferred embodiment of routeinformation.

FIG. 14 is a schematic diagram of a preferred embodiment of map androute information.

FIG. 15 is a flow diagram of a preferred embodiment of step 510 shown inFIG. 5.

FIG. 16 is a schematic diagram of a preferred embodiment of a map.

FIG. 17 is a schematic diagram of a preferred embodiment of an end pointfirst region.

FIG. 18 is a schematic diagram of a generalized embodiment of an endpoint first region.

FIG. 19 is a flow diagram of a preferred embodiment of a prioritizedorder of transmission of navigation information.

FIG. 20 is a flow diagram of an alternative embodiment of a prioritizedorder of transmission of navigation information.

FIG. 21 is a flow diagram of an alternative embodiment of a prioritizedorder of transmission of navigation information.

FIG. 22 is a flow diagram of an alternative embodiment of a prioritizedorder of transmission of navigation information.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

FIG. 1 is a schematic view of an illustrative embodiment of a motorvehicle 100 along with various communications and computer resources,including a wireless communications network 106. Wireless network 106can be any kind of wireless network, including but limited to anycellular telephone network using, for example, any one of the followingstandards: CDMA, TDMA, GSM, AMPS, PCS, analog, and/or W-CDMA.

In some embodiments, a service provider 108 communicates with motorvehicle 100. A wireless network 106 can be used facilitatecommunications between service provider 108 and motor vehicle 100.Service provider 108 can communicate with wireless network 106 in anumber of different ways. In some embodiments, service provider 108communicates with wireless network 106 wirelessly. In other embodiments,service provider 108 is directly connected to one or more elements ofwireless network 106, and in still other embodiments, service provider108 communicates with wireless network 106 by using the Internet 110. Insome embodiments, service provider 108 can use more than one method ofcommunicating with wireless network 106 or use other methods asback-ups.

Motor vehicle 100 also includes at least one wheel 120 adapted tocontact a road surface, an engine 122, a body or chassis 124 and apassenger cabin 126, which is adapted to accommodate at least one humanpassenger.

FIG. 2 is a schematic diagram of a preferred embodiment of a serviceprovider 108. In some embodiments, service provider 108 can include acomputer system 202 and a database 204 in communication with computersystem 202. The term “computer system” refers to the computing resourcesof a single computer, a portion of the computing resources of a singlecomputer, and/or two or more computers in communication with oneanother, also any of these resources can be operated by one or morehuman users. In a preferred embodiment, computer system 202 includes aserver.

Computer system 202 preferably communicates with database 204. Database204 can include any kind of storage device, including but not limitedmagnetic, optical, magneto-optical, and/or memory, including volatilememory and non-volatile memory. In some embodiments, database 204 isintegral with computer system 202 and in other embodiments, database 204is separate from computer system 202 and communicates with computersystem 202. In some embodiments, database 204 is used to storenavigation information.

The term “navigation information” refers to any information that can beused to assist in determining a location or providing directions to alocation. Some examples of navigation information include streetaddresses, street names, street or address numbers, apartment or suitenumbers, intersection information, points of interest, parks, anypolitical or geographical subdivision including town, township,province, prefecture, city, state, district, ZIP or postal code, andcountry. Navigation information can also include commercial informationincluding business and restaurant names, commercial districts, shoppingcenters, and parking facilities. Navigation information can also includegeographical information, including information obtained from any GlobalNavigational Satellite infrastructure (GNSS), including GlobalPositioning System or Satellite (GPS), Glonass (Russian) and/or Galileo(European). The term “GPS” is used to denote any global navigationalsatellite system. Navigation information can include one item ofinformation, as well as a combination of several items of information.

In some embodiments, an update resource 206 is in communication withservice provider 108. Update resource 206 can provide updates,revisions, edits and other modifications to service provider 108. Insome cases, update resource 206 provides updated navigation information.In some embodiments, update resource 206 provides automated updates. Insome embodiments, update resource provides periodic updates.

Some embodiments include a billing system 208 in communication withservice provider 108. Billing system 208 can include account informationfor users and can interact with service provider 108 to prepare andgenerate bills. Billing system 208 can provide electronic billing ortraditional billing by mail. In some embodiments, billing system 208 isa part of service provider 108 and billing system 208 uses resourcesassociated with service provider 108. In other embodiments, billingsystem 208 is separate from service provider 108 and communicates withservice provider 108.

Billing system 208 can interact with service provider 108 in a number ofdifferent ways. In some embodiments, billing system 208 operates on atransactional basis. In this mode, billing system 208 keeps track of asubscriber's use of service provider 108. In some cases, billing system208 tracks or stores particular transactions or events associated withthose transactions. For example, in one embodiment, billing system 208tracks or stores requests for navigation information. These requests fornavigation information can be related to a particular transaction, andbilling system 208 can use these requests to track or store informationrelated to the transaction. Billing system 208 can associate thoserequests with a subscriber and create a bill entry.

In some embodiments, billing system 208 tracks or stores the length oftime a subscriber uses or interacts with service provider 108. In thisembodiment, billing system 108 tracks or stores how long a subscriberuses are interacts with service provider 108. In some cases, a discreetmeasure of time, for example, a minute or any fraction or multiple, canbe used to record or track a subscriber's use or interaction withservice provider 108. This measure of time can be used to compute a feeand prepare a bill entry.

In some embodiments, subscribers are permitted to use or interact withservice provider 108 any number of times for a set duration. Forexample, it is possible for subscribers to have weekly, monthly,quarterly or annual agreements with service provider 108 so that, duringthose agreed to periods, subscribers can use or interact with serviceprovider 108 as often as they choose. Other durations of time can alsobe established. In some of these cases, subscribers have unlimitedaccess to service provider 108 for that pre-selected duration of time.In other cases, subscribers have certain unlimited basic usage rightsfor that duration of time, but must pay additional fees for premiumservices.

One or more of the different types of billing arrangements can be usedfor a particular subscriber. It is also possible to provide one type ofbilling arrangement to one subscriber while providing a differentbilling arrangement to another subscriber.

Billing system 208 and service provider 108 can communicate with oneanother to manage subscriber access and to assist in preparing bills tosubscribers. In some embodiments, billing system 208 can retrieveinformation from service provider 108 to create bill entries or entirebills. However, it is also possible for service provider to sendinformation to billing system 208 related to a subscriber's activitiesso that billing system 208 can create bill entries or entire bills.

In some cases, service provider 108 will request information orpermission from billing system 208 before preparing navigationinformation. In these cases, service provider 108 sends a request forpermission to billing system 208 after a request for navigationinformation has been received from a subscriber. After receiving therequest for permission from service provider 108, billing system 208 candetermine if the subscriber has a valid account. In some cases, a validaccount is an account that is not overdue, an account that has beenpre-paid, or an account with an associated credit card. If the accountis valid for some reason, billing system 208 provides permission toservice provider or can inform service provider 108 that thesubscriber's account is valid. After receiving permission, serviceprovider 108 continues to process the subscriber's request andeventually respond to the subscriber.

Either or both service provider 108 or billing system 208 can use anumber of different techniques to insure that the proper party is billedfor various transactions. In one embodiment, information related to anOn-Board Unit (disclosed below) is used to associate a particulartransaction, interaction or subscription with a particular account. Inanother embodiment, information related to a wireless network is used toassociate a particular transaction, interaction or subscription with aparticular account. Some examples of information related to a wirelessnetwork include the following: Mobile Identification Number (MIN),calling party's number, Electronic or Equipment Identifier (EID), and/orElectronic Serial Number (ESN).

FIG. 3 is a schematic diagram of several devices that are associatedwith motor vehicle 100. Central unit 302 can include a number of portsthat facilitate the input and output of information and power. The term“port” means any interface or shared boundary between two conductors. Insome cases, ports can facilitate the insertion and removal ofconductors. Examples of these types of ports include mechanicalconnectors. In other cases, ports are interfaces that generally do notprovide easy insertion or removal. Examples of these types of portsinclude soldering or electron traces on circuit boards.

All of the following ports and provisions associated with central unit302 are optional. Some embodiments may include a given port orassociated provision, while others may exclude it. The followingdescription discloses many of the possible parts and provisions that canbe used, however, it should be kept in mind that not every part orprovision must be used in a given embodiment. Central unit 302 includesa wireless network antenna port 304 that is designed to receiveinformation from a wireless network antenna 306, a GPS antenna port 308designed to receive information from a GPS antenna 310, a radio antennaport 312 designed to receive information from a radio antenna 314.

Central unit 302 can also include a number of items that facilitatehuman interaction. To receive vocal information from a user, centralunit 302 can include a microphone port 316 that is capable ofcommunicating with a microphone 318. Central unit 302 can also includean audio port 320 that is designed to send audio information to one ormore speakers 322 or audio devices. In some embodiments, microphone port312 and audio port 316 are conductors associated with a single physicalconnector. For example, microphone port 312 and audio port 316 can befemale conductors of a multi-channel coaxial plug, like a standard 2.5mm headset plug.

In order to provide visual information to a user, central unit 302 caninclude a display port 324 that is capable of interacting with a displaydevice 326. To receive input from a user, central unit 302 can includean input port 328. Input port 328 can communicate with input device 330.In some embodiments, display device 326 can also receive input from auser. In some embodiments, display device 326 includes a touch screenthat can receive input and in other embodiments, display device 326includes a number of buttons that can receive input. In someembodiments, display device 326 includes both a touch screen andbuttons. As shown in FIG. 3, user input received by display device 326can also communicate with input port 328.

A power port 332 can connect central unit 302 to a power supply 334. Inthe embodiment shown in FIG. 3, power supply 334 is a battery.

Central unit 302 can also include provisions to communicate with awireless telephone. Any system can be used to facilitate thiscommunication with a wireless telephone; however, a low power radiofrequency system is preferred. In an exemplary embodiment, a wirelesslocal or personal area network using the Bluetooth® protocol is used tofacilitate communication with a wireless telephone. In the exemplaryembodiment shown in FIG. 3, central unit 302 includes a local wirelessnetwork antenna port 336 that is designed to communicate with a localwireless network antenna 338, which in turn, is designed to communicatewirelessly with wireless telephone 340.

Referring to FIGS. 1 and 3, there are two ways in which central unit 302can communicate with wireless network 106. In some embodiments, centralunit 302 includes provisions that permit central unit 302 to act as awireless telephone. In these embodiments, central unit 302 communicatesdirectly with wireless network 106 and can use wireless network antennaport 304 and wireless network antenna 306 to assist with thiscommunication. In other embodiments, central unit 302 communicates withwireless telephone 340, which in turn, communicates with wirelessnetwork 106. In these other embodiments, central unit 302 can use localwireless antenna port 336 and associated local wireless network antenna338 to assist in facilitating communications with wireless telephone340. One or both of these methods can be used by central unit 302 tocommunicate with wireless network 106.

Central unit 302 can also include memory, data storage provisionsincluding one or more databases and/or one or more processors.

In some embodiments, all or most of the items shown in FIG. 3 are housedin a single case or unit. In other embodiments, the various items shownin FIG. 3 are not housed in a single physical case, but instead, aredistributed throughout motor vehicle 100 (see FIG. 1) and communicatewith one another via known wired or wireless methods. For example, in asystem where one or more items communicate wirelessly, the Bluetooth®protocol can be used.

FIG. 4 is a preferred embodiment of an interior 400 of passenger cabin126 of motor vehicle 100 (see FIG. 1). Interior 400 includes steeringwheel 402, driver's seat 404, shifter or gear selector 406, dashboard408 and center console 410. Center console 410 includes an upper portion412 and a lower portion 414. In some embodiments, lower portion 414includes radio and/or audio controls. Preferably, upper portion 412includes display 416. In some embodiments, upper portion 412 includes amulti-function unit that can communicate or control an audio system, aclimate control system and/or a navigation system.

In an exemplary embodiment, display 416 is used as display device 326,shown schematically in FIG. 3. Also in the exemplary embodiment, centralunit 302 or portions of central unit 302 is disposed behind display 416.In some embodiments, display 416 can include a touch screen and in someembodiments, buttons can be disposed next to display 416.

In one embodiment, central unit 302 includes provisions that allowcentral unit 302 to act as a hands free telephone system. In thisregard, microphone 314 can be placed in a discreet and somewhat hiddenlocation in passenger cabin 126 (see FIG. 1) of motor vehicle 100 (seeFIG. 1). Other components are preferably placed out of plain sight.

Some embodiments provide a system and method managing navigationinformation. FIG. 5 is a flow diagram of a preferred embodiment of asystem and method for managing navigation information.

In the embodiment shown in FIG. 5, certain steps are associated withOn-Board Unit (referred to as “OBU”) 500 and certain steps areassociated with service provider 108. Preferably, those steps associatedwith OBU 500 are performed on or by OBU 500 and those steps associatedwith service provider 108 are performed on or by service provider 108.However, this is not necessarily the case, and those steps associatedwith OBU 500 can be performed on or by service provider 108 or someother resource, and those steps associated with service provider 108 canbe performed on or by OBU 500 or some other resource.

OBU 500 is a device or provision associated with motor vehicle 100. Insome embodiments, OBU 500 includes provisions that permit OBU 500 toreceive information. In some embodiments, OBU 500 can store informationin a memory or computer readable media. In some embodiments, OBU 500includes provisions that permit OBU 500 to process information. In someembodiments, OBU 500 includes provisions that permit OBU 500 to displayinformation. In some embodiments, OBU 500 includes provisions thatpermit OBU 500 to receive information from a user. In some embodiments,OBU 500 includes provisions that permit OBU 500 to receive informationfrom a wireless network. In some embodiments, OBU 500 includesprovisions that permit OBU 500 to interact with a user. In someembodiments, OBU 500 includes a combination of two or more of the aboveprovisions.

Different embodiments can include different elements or features. Forsimplicity, the term, “On-Board Unit” (OBU) is used to refer to thoseelements or components that are associated with motor vehicle 100 (seeFIG. 1) for a particular embodiment. In an exemplary embodiment, OBU 500comprises one or more facilities of central unit 302 (see FIG. 3). OBUcan also include one or more of the items shown in FIG. 3, for example,central unit 302, display 326, and/or input device 330.

Preferably, as shown in FIG. 5, the process begins when an input isreceived in step 502. Any form of input can be received in step 502. Insome cases, the input is in the form of one or more buttons beingpressed, and/or interaction with a touch screen associated with displaydevice 326 (see FIG. 3). In some cases, a combination of input frombuttons and/or touch screen interaction is received.

It is also possible for voice information to be received in step 502.Any known speech recognition process or program can be utilized toconvert spoken words, phrases and/or numbers into a machine readableformat. Preferably, the IBM® embedded Via Voice speech recognitionengine is used.

In step 504, OBU 500 analyzes and processes the information received instep 502 and prepares a request for navigation information. In step 506,OBU 500 sends a request for navigation information. In step 508, serviceprovider 108 receives a request for navigation information. In step 510,service provider 108 analyzes and processes the request for navigationinformation and prepares a response to the request. In step 512, serviceprovider 108 sends the requested navigation information to OBU 500.

Step 514 is an optional step. In step 514, service provider memorializesthe transaction. In some embodiments, the request is memorialized, inother embodiments, the response is memorialized and in still otherembodiments, both the request and the response are memorialized. It isalso possible to include time, date and location stamps. Thismemorialized information can be used to interact with billing system 208(see FIG. 2).

In some embodiments, service provider 108 can prepare navigationinformation for delivery. Preferably, this preparation step occurs instep 510 after a request for navigation services has been received. Oneor more different processes or techniques can be used to preparenavigation information for delivery. FIG. 15, which is a flow diagram ofa preferred embodiment of step 510, shows several processes that can beused by service provider 108. In the embodiment shown in FIG. 15, someof the processes include auto scale 1502, smart route storage 1504 andselect absolute or relative coordinates 1506. In some embodiments, oneof the processes is used. In other embodiments, two or more processesare used, and in still other embodiments, all of the processes are used.Furthermore, the various process steps can occur in any desired order.

The process to prepare navigation information 510 can include one ormore steps or processes. One of these processes is a process wheredifferent elements of a map are encoded or expressed using absolute orrelative coordinates. FIG. 6 is a flow diagram of a preferred embodimentof a method for preparing navigation information. This method can beused alone or in conjunction with other methods. Preferably, thisprocess begins with a step 602 of determining an overall map or route.After the overall map or route has been selected, the map or route ispreferably divided into two or more smaller portions. Any desiredapproach can be used to divide the map or route, and one suitableexample is shown in FIG. 7.

A particular map portion is selected in step 604. After this map portionhas been selected, the process determines which coordinate system,either absolute or relative, will encode or express the various mapfeatures associated with the map portion most efficiently. The selectionof absolute or relative coordinates is discussed in greater detailbelow. If a relative coordinate system more efficiently encodes orexpresses the information, then a relative coordinate system is used,and the various map features associated with the selected map portionare encoded in relative coordinates 608. On the other hand, if absolutecoordinates are more efficient, than the various map features associatedwith the selected map portion are encoded using absolute coordinates610.

After the selected map portion has been encoded, the process, in step612, determines if the map is complete or if there are other mapportions left to encode. If the map is incomplete, the process returnsto step 604 where another map portion that has yet to be encoded isselected. If the process determines that the map is complete and thatall of the map portions have been encoded, the process ends. In someembodiments, the map portions are assembled “on the fly,” that is,during the encoding process. In other embodiments, the map portions areencoded and at the very end, all of the various map portions areassembled in step 614.

After the overall map has been determined in step 602, the process shownin FIG. 6, attempts to reduce the overall amount of information thatneeds to be transmitted. One way to accomplish this reduction in data isto use relative or absolute coordinates to define various objects on amap.

In an absolute coordinate system, each coordinate is expressedindependently from other coordinates. The information associated with aparticular coordinate is sufficient to define the coordinate on a map orregion.

Preferably, an absolute coordinate includes two bytes of data. One byteis used for the value of one axis, and the other byte is used for thevalue of the other axis. For example, a single absolute coordinate canbe expressed as (X1, Y1) where X1 is the x-axis value and Y1 is they-axis value of the coordinate. Preferably, one byte is used to defineX1 and a second byte is used to define Y1. Thus, if absolute coordinatesare used, two bytes are used to define each coordinate. If a map were toinclude two coordinates, then four bytes would be used to the twocoordinates. For example, the first coordinate would be (X1, Y1) and thesecond coordinate would be (X2, Y2). As noted above, two bytes would beused to define X1 and Y1. Two bytes would also be used to define thesecond coordinate; one byte for X2 and a second byte for Y2. Thus, inthis simple example, a total of four bytes would be used to define twocoordinates using the absolute coordinate system.

In contrast, relative coordinates preferably use an initial absolutecoordinate, and one or more subsequent coordinates that are defined inrelation to the initial coordinate. For example, consider a situationwhere two coordinates are defined using a relative coordinate system.The first coordinate (X3, Y3) would be defined using an absolutecoordinate system and the second coordinate, (X4, Y4) would be definedrelative to the first coordinate. In a preferred embodiment, the valuesassociated with the second coordinate are expressed as differences ordisplacements from the first coordinate. In this embodiment, the X-axisvalue would be X4-X3 or dX and the Y-axis value would be Y4-Y3 or dY. Inthis example, the first coordinate would be (X3, Y3) and the secondcoordinate would be expressed as (dX, dY). Preferably, the expression(dX, dY) is encoded as a single byte.

In a preferred embodiment, a portion of the byte is used to express dXand another portion of the byte is used to express dY. In an exemplaryembodiment, the byte is divided into two halves, and the first half isused to express dX while the second half is used to express dY. Anysuitable byte length can be used. For example, in some cases, a bytecomprises eight (8) bits. In this case, in an exemplary embodiment, thefirst four bits would be used to express dX and the next four bits wouldbe used to express dY. In another example, a byte is comprised of 16bits. Here, the first eight bits would be used to express dX and thenext eight bits would be used to express dY. In other cases, bytes caninclude 32, 64, 128, 256, 512, 1024 or any other number of bits.Regardless of the size of the byte, the principles of encoding a twoaxis displacement into a single byte can be applied.

Returning to the simple example, two bytes are required when using anabsolute coordinate system while only three bytes are required whenusing a relative coordinate system. Thus, in this simple example, therelative coordinate system more efficiently encodes the data. There arecases where an absolute coordinate system is advantageous. One exampleis a long, straight road. The road can be defined by its two end points.In absolute coordinates, the two end points would require four bytes.However, in relative coordinates, many intermediate points may berequired. This is because of the limited bit length available for eachdisplacement step. Because of this, a relative coordinate system mayrequire many intermediate points to define the entire road. In sum, bothsystems have their advantages and disadvantages. There are cases whereabsolute coordinates more efficiently encode a particular item ofnavigation information and there are cases where relative coordinatesmore efficiently express an item of navigation information. Preferably,the more efficient system is selected, as disclosed below.

In some embodiments, the entire map is represented in absolute orrelative coordinates. However, in other embodiments, portions of the mapare selected and these individual portions are represented in eitherabsolute or relative coordinates. FIG. 7 is schematic diagram of anexample of a map 702 that has been divided into regions. As shown inFIG. 7, map 702 includes some regions where absolute coordinates havebeen used. These regions are symbolized on map 702 with the letter “A.”Map 702 also includes regions where relative coordinates have been used.These regions are represented in map 702 with the letter “R.”

Preferably, the coordinate system that requires the smallest amount ofinformation to accurately represent the relevant data for thatparticular region is selected. Thus, if a relative coordinate systemrequires less information to define the desired map elements or aparticular region, then a relative coordinate system is used. On theother hard, if an absolute coordinate system requires less information,then an absolute coordinate system is used.

In some embodiments, individual map features are represented in onecoordinate system, while other similar map features are representedusing the other coordinate system. A map feature is any item or entitythat can appear on a map. Some examples of map features include streetsor roads, landmarks, points of interest, parks, commercial areas,parking lots, and geographic features like mountain ranges and bodies ofwater. FIG. 8 is an example of distinct coordinate systems representingsimilar map features. Consider, for example, map portion 802, whichincludes a first road 804 and a second road 806. First road 804generally extends west to east, while second road 806 generally extendsnorth to south. First and second roads 804 and 806 meet at intersection808.

In this example, it is assumed that 804 can be represented with lessinformation using a relative coordinate system than if an absolutecoordinate system were used. Because of this, a relative coordinatesystem is used to represent first road 804. In contrast, it is assumedthat second road 806 can be represented in absolute coordinates moreefficiently, that is, with less data, than with relative coordinates.Thus, absolute coordinates would be selected for second road 806. Inthis way, similar map features within a particular map region arerepresented using different coordinate systems.

In some embodiments, different portions of the same map feature can berepresented in different coordinate systems. FIG. 9 is a schematicdiagram of an example map region 902. Although any map feature can berepresented with two different coordinate systems, FIG. 9 provides anexample of a road 904 that is represented by two different coordinatesystems. Road 904 includes a first portion 906 and a second portion 908.In the example shown in FIG. 9, first portion 906 is more efficientlyrepresented using relative coordinates. That means that first portion906 can be represented by less information if relative coordinates areused, than if absolute coordinates are used. In contrast, second portion908 is more efficiently represented in absolute coordinates. Preferably,in order to most efficiently encode road 904, a relative coordinatesystem is used to represent first portion 906 and an absolute coordinatesystem is used to represent second portion 908.

In some embodiments, different axes of a single map feature arerepresented using different coordinate systems. One example of this is asituation where the X-axis of a particular map feature is moreefficiently represented using absolute coordinates and the Y-axis of thesame map feature is more efficiently represented using relativecoordinates. In this case, the X-axis of the map feature can berepresented in absolute coordinates while the Y-axis can be representedin relative coordinates.

Some embodiments include provisions to reduce the size of informationtransmitted from service provider 108 to OBU 500. Although the followingprocedure can be performed in any step shown in FIG. 5, it is preferredthat the following procedure be performed in step 510.

The following procedure reduces the size of information by removingduplicate information. Referring to FIG. 10, which is an example of mapwith five roads labeled E, F, G, L M and N. Each of the roads arecomprised of one or more segments. For example, road E is comprised ofsegments E1, E2, E3, E4, E5 and E6. Road F is comprised of segments F1,F2, F3, F4, F5, F6, F7, F8 and F9. The other roads are also comprised ofvarious segments as shown in FIG. 10.

Given the map data of FIG. 10, consider an example where a route isplotted. FIG. 11 is a schematic diagram of FIG. 10 with route 1102.Route 1102 includes the following segments: N1, N2, N3, E3, L4, L5, L6and L7.

In some embodiments, information regarding all of the segments of all ofthe roads associated with map 1002 is sent and then information relatedto the segments associated with route 1102. To demonstrate this,reference is made to Figures BC and BD. Figure BC is a schematic diagramof information related to map 1002. Each of the boxes in Figure BCcontains a segment label, and those segment labels represent informationused to define the segment. In some cases, each segment is defined by aninitial XY coordinate and a final XY coordinate. In other cases, eachsegment is defined by an initial XY coordinate and a displacement.

Regardless of how each segment is defined, six segments related to roadE, nine segments related to road F, five segments related to road G,seven segments related to road L, four segments related to road M andthree segments related to road N for a total of thirty four (34)segments are established and prepared for transmission.

After information related to map 1002 has been prepared and/or sent,information related to route 1102 is prepared. As disclosed above and asshown in FIG. 11, example route 1102 includes segments N1, N2, N3, E3,L4, L5, L6 and L7, for a total of eight (8) segments. Informationrelated to the segments associated with route 1102 is then preparedand/or sent. In this example, information related to a total of fortytwo (42) segments required to define map 1002 and route 1102 on map1002. This is because thirty four (34) segments are required to definemap 1002 and eight (8) segments are required to define route 1102.Adding thirty four (34) and eight (8) yields a total of forty two (42)segments. Schematically, this process can be understood by consideringthe segments contained in FIG. 12 being transmitted followed by thesegments contained in FIG. 13. Notice that the segments used to defineroute 1102 are redundantly transmitted, first to define map 1002 andthen to define route 1102.

It is possible to reduce the number of total segments required to defineroute 1102 in map 1002. FIG. 14 is a schematic diagram of a preferredembodiment of a method for preparing and/or sending map and routeinformation. In this embodiment, route information is prepared and isestablished as the first set of information. Map information other thanthe route information is placed after the route information.

Returning to the examples shown in FIGS. 10 and 11, recall thatinformation associated with route 1102 is expressed as segments: N1, N2,N3, E3, L4, L5, L6 and L7, as shown in FIG. 13. Preferably, this routeinformation is placed or transmitted first. As shown in FIG. 14, whichis a schematic diagram of a preferred embodiment of information relatedto map 1002 and route 1102, information related to route 1102 is placedbefore other information. Other non-route information is placed afterroute 1102 information. In some embodiments, a separation character isplaced between route 1102 information and other non-route information.In other embodiments, a header is provided before any information issent. This header can include information regarding the end of route1102 information and the beginning of other non-route information. Insome cases, the header can include the number of segments of route 1102information. In other cases, the header can include a name, label orother indicia of the last segment of route information.

This results in a total of thirty four (34) segments. Using thistechnique, the redundancy of expressing and transmitting routeinformation is eliminated, and only 34 segments are required to expressmap 1002 and route 1102 as opposed to forty two (42) segments.

In some embodiments, different portions of a map or route are definedusing different levels of detail. In some cases, certain regions aredefined in greater detail than other regions. Referring to FIG. 16,which is a preferred embodiment of an example map 1602, a route 1604 hasbeen determined. In some embodiments, there are two regions withdifferent levels of detail, in other embodiments, there are three ormore regions that have different levels of detail. In the embodimentshown in FIG. 16, there are three regions with different levels ofdetail.

A first region 1606 proximate route 1604 is encoded or established witha first level of detail. Preferably, this first level of detailaccurately portrays many map features, for example, small side streetsand roads, detailed information regarding intersections, points ofinterest, information regarding businesses and other detailedinformation. In some embodiments, this first level of detail includesfull detail or all available information.

First region 1606 can extend a predetermined distance from route 1604.In some cases, first region 1606 extends further away from route 1604 insome places than in other places. Preferably, first region 1606 extendsfurther away from route 1604 at its endpoints than at other portions ofroute 1604.

Referring to the example in FIG. 16, route 1604 includes a startingpoint 1608 and an destination point 1610. Starting point 1608 ispreferably used to represent the starting point of route 1604, andincludes a starting point first region 1612 disposed about startingpoint 1608. In some cases, like the embodiment shown in FIG. 16,starting point first region 1612 surrounds starting point 1608. In otherembodiments, starting point first region 1612 does not completelysurround starting point 1608.

Similarly, destination point 1610 is used to represent the destinationpoint of route 1604. Preferably, destination point 1610 includes adestination point first region 1614 disposed about destination point1610. In some cases, like the embodiment shown in FIG. 16, destinationpoint first region 1614 surrounds destination point 1610. In otherembodiments, destination point first region 1614 does not completelysurround destination point 1610.

Starting point 1608 and destination point 1610 can be referred to as endpoints. End points are disposed at outer ends of a given route.Preferably, the size of first region 1606 is different near the endpoints than for other points along route 1604. End point first regionscan also have different shapes than the shape of first region 1606 alongroute 1604.

FIGS. 17 and 18 are schematic diagrams of embodiments of end point firstregions. The embodiments of end points shown in FIGS. 17 and 18 can beapplied to ether starting point 1608 or destination point 1610 or both.An end point 1702 can be seen in FIG. 17, along with a preferredembodiment of an destination point first region 1704 associated with endpoint 1702. Although any arbitrary shape can be selected and used as endpoint first region 1702, the box shape shown in FIG. 17 is preferred.

As shown in FIG. 17, end point first region 1704 includes a boundarycomprising first side 1710, second side 1712, third side 1714 and forthside 1716. Although the sides can assume any desired orientation,preferably, first and second sides 1710 and 1712, respectively, arepreferably disposed on either side of end point 1702 and third andfourth sides 1714 and 1716, respectively, are disposed above and belowend point 1702. In some embodiments, first side 1710 and second side1712 are vertical, in other embodiments, they are angled, curved orirregular. In some embodiments, third side 1714 and fourth side 1716 arehorizontal, in other embodiments, they are angled, curved or irregular.

In the embodiment shown in FIG. 17, First side 1710 is spaced from endpoint 1702 a distance of about 1706 and second side is also spaced adistance of about 1706 from end point 1702. Third side 1714 is spacedfrom end point 1702 a distance of about 1708 and fourth side 1716 isspaced from end point 1702 a distance of about 1708. This provides anend point first region 1704 having dimensions 2*1706×2*1708, where 1706and 1708 are not literal distance dimensions or lengths, but ratherrepresent the respective distances between a side and end point 1702. Insome embodiments, end point 1702 is roughly centered within end pointfirst region 1704, in other embodiments, end point 1702 is disposed at alocation that is not centered about end point first region 1704.Referring to FIGS. 16 and 17, the principles and characteristics of endpoint first region 1704 can be applied to either starting point firstregion DA12 or destination point first region 1614 or both.

FIG. 18 shows another embodiment of an end point first region 1804 andits associated end point 1802. In this embodiment, end point firstregion 1804 has a generalized shape. Different portions of end pointfirst region 1804 are spaced different distances from end point 1802than other portions. For example, first portion 1810 is spaced from endpoint 1802 by a distance of about 1806 and second portion 1812 is spacedfrom end point 1802 by a distance of about 1808.

Referring to FIGS. 16 and 18, the principles and characteristics of endpoint first region 1804 can be applied to either starting point firstregion 1612 or destination point first region 1614 or both.

Referring to FIGS. 16 to 18, a comparison can be made between the extentor relative size of the first region 1606 associated with route 1604 andthe first region associated with an end point. In a preferredembodiment, the relative size of a portion of the first regionassociated with an end point is larger than the size of a first regionassociated with route 1604. In some cases, a portion of the first regionassociated with an end point is larger than the first region associatedwith a route, while other portions of the first region associated withan end point are smaller than the first region associated with a route.In other cases, the size of the first region associated with an endpoint is larger in every direction than the size of the first regionassociated with a route. These features can be observed with referenceto the Figures.

Referring to FIGS. 16 to 18, the relative sizes of first region 1606associated with route 1604, starting point first region 1612 anddestination point first region 1614 are considered. First region 1606generally extends in a distance normal or perpendicular to route 1604.As route 1604 bends and turns, first region 1606 follows this meanderingpath and the outer boundaries of first region 1606 generally remainparallel to route 1604 on either side. As shown in FIG. 16, theboundaries of first region 1606 can be truncated, cut, or otherwisemodified around turns. These modifications can be made to facilitaterapid computation of the size and boundary of first region 1606, orthese modifications can be made when an approximation, as opposed to anexact distance, is desired. Given these variations, portions of firstregion 1606 extend a distance 1618 away from route 1604. It is possiblefor some portions of first region 1606 to extend further away from route1604 than distance 1618, and it is also possible for some other portionsof first region 1606 to remain closer to route 1604 than distance 1618.This is particularly true at bends or curves, but these variations canalso occur on straight portions of route 1604 as well.

Distance 1618, which is the perpendicular distance from route 1604 to anouter boundary of first route 1606 along a portion of first route 1606,can be used to determine the relative general width of a portion offirst region 1606. Preferably, first region 1606 extends in roughlyequal distances on one side of route 1604 as on the other side. Althoughthese distances can vary, equal distances are generally preferred. Giventhis arrangement, the width of first region 1606 is approximately twicedistance 1618 or 2*(1618), where 1618 is not a literal number or lengthmeasurement, but a representation of the distance from route 1604 to theouter boundary of first region 1606, as shown in FIG. 16.

The width of first region 1606 can be compared with the size of a firstregion associated with an end point. In some embodiments, starting pointfirst region 1612 has the characteristics of end point first region 1704as shown in FIG. 17. In this example, end point first region 1704includes first and second sides 1710 and 1712. These sides are spaced adistance 1706 from end point 1702. In some embodiments, the distance1706 from end point 1702 to first side 1710 is greater than the distance1618 between route 1604 and an outer boundary of first region 1606.

End point first region 1704 also includes third and fourth sides 1714and 1716, respectively. The distance between these sides and end point1703 is 1708. In some embodiments, the distance 1708 from end point 1702to third side 1714 is greater than the distance 1618 between route 1604and an outer boundary of first region 1606.

When distance 1706 and 1708 are both considered and compared withdistance 1618, other embodiments can be observed. In some embodiments,distance 1706 is roughly equal to distance 1708. This provides agenerally square shaped end point first region 1704. In otherembodiments, the distance 1706 is not equal to distance 1708, resultingin a rectangular end point first region 1704. In some embodiments, bothdistances 1706 and 1708 are greater than distance 1618. In otherembodiments, one of the distances 1706 or 1708 is greater than distance1618, while the other distance is less than distance 1618. In somealternative embodiments, distance 1618 is greater than either distance1706 or 1708. In a preferred embodiment, both distances 1706 and 1708are greater than distance 1618.

FIG. 18 shows another embodiment of an end point 1802 and its associatedend point first region 1804, as disclosed above. Recall that end pointfirst region 1802 includes a first portion 1810 that is spaced adistance 1806 from end point 1802 and a second portion 1812 that isspaced a distance 1808 from end point 1802.

These distances 1810 and 1812, can be compared with distance 1618. Insome embodiments, both distances 1810 and 1812 are greater than distance1618. In other embodiments, one of the distances 1810 or 1812 is greaterthan distance 1618, while the other distance is less than distance 1618.In some alternative embodiments, distance 1618 is greater than eitherdistance 1810 or 1812.

In addition to a first region, some embodiments also include a secondregion 1620. Preferably, second region 1620 includes less detail thanfirst region 1606. In some embodiments, this means that at least oneitem or class of navigation information is omitted from second region1620 as compared to first region 1606. For example, small side streets,one class or type of navigation information, may be omitted in secondregion 1620 but may be represented in first region 1606. Business namescould be another example. First region 1606 may represent or includecertain business names, while second region 1620 omits these items ofnavigation information. In a preferred embodiment, second region 1620includes major arteries, like interstate highways, major geographicfeatures, like major bodies of water, and other major or significantfeatures like bridges, national parks, airports, and major politicalsubdivisions, like state lines and city limits.

In addition to first region 1606 and second region 1620, someembodiments include a third region 1616. Preferably, third region 1616includes all areas or portions of map 1602 that is not defined by anyother portion. In the embodiment shown in FIG. 16, third region 1616includes portions of map 1602 that is not described or defined by firstregion 1606 or second region 1620. Preferably, third region 1616includes less detail than second region 1620. Again, items or classes ofnavigation information can be omitted in third region 1616 that isdescribed in second region 1620. In a preferred embodiment, third region1616 includes no navigation information.

This process formats and prepares navigation information for efficienttransmission. Information far from a desired route is simplified oreliminated and information near the desired route is provided in greaterdetail. Essential and useful information near the route is retained,while information far from the route is simplified or condensed. In thisway, essential and useful information is made available, whileinformation that is not likely to be used is discarded or simplified.

Navigation information can also be transmitted in a way to improve theavailability of the navigation information and to provide usefulinformation more quickly to a user. In one embodiment, this isaccomplished by sending the navigation information in a particularorder.

FIGS. 19 to 22 are flow diagrams of various different embodimentsshowing different ways to transmit navigation information to an OBU.Referring to FIGS. 5, 16 and 19 to 22, there are preferably fourdiscreet sets of data that are sent from service provider 108 to OBU500. These four sets of data include: “Entire Route Map,” “Detail ofStarting Point,” “Detail of Destination Point,” and “Detail AlongRoute.”

In a preferred embodiment, “Entire Route Map,” refers to informationrelated to route 1604. This information can be used to define route1604. “Detail of Starting Point” refers to information related tostarting point first region 1612. This information provides details ofthe area near starting point 1608. Similarly, “Detail of DestinationPoint” provides information related to destination point first region1614. This information provides details of the area near destinationpoint 1610. “Detail Along Route” provides information related to firstregion 1606 associated with route 1604. Preferably, these four discreetitems of data are sent in a predetermined order.

In the embodiment shown in FIG. 19, Entire Route Map is transmittedfirst, then Detail of Starting Point, then Detail of Destination Pointand finally, Detail Along Route. In this embodiment, the intent is toallow the user to commence the journey as soon as possible. Thus, theEntire Route Map, which would include directions along the route, istransmitted first. In some cases, this allows the user to begin drivingwithout having to wait until all of the information is sent to the OBU.

In the embodiment shown in FIG. 20, Entire Route Map is transmittedfirst, then Detail of Starting Point, then Detail Along Route, andfinally, Detail of Destination Point. This embodiment is similar to theembodiment shown in FIG. 19 except the last two steps are reversed. Thisembodiment can be used when the user is familiar with the destinationpoint and it would be more helpful to the user to receive details alongthe route before details of the destination are received.

In the embodiment shown in FIG. 21, Detail of Starting Point, istransmitted first, then Entire Route Map, then Detail of DestinationPoint and finally, Detail Along Route. This embodiment can be used whenthe user is unfamiliar with the current surroundings and the currentstarting point. Details of the starting point may be helpful inassisting the user in finding the route. In this case, details of thestarting point would be the most helpful information and would help theuser to commence the journey as soon as possible.

In the embodiment shown in FIG. 22, Detail of Destination Point, istransmitted first, then Entire Route Map, then Detail of Starting Pointand finally, Detail Along Route. This embodiment can be used when theuser is unfamiliar with the destination point and wants to confirm thatthe navigation information is correct and is likely to provide correctdriving directions. In these instances, details of the destination wouldbe the most helpful information for the user to receive first.

The above embodiments are exemplary. Clearly other embodiments are alsopossible, and the order of delivery can be adjusted or selected to suita particular need or situation. Referring to FIGS. 19 to 22 and FIG. 5,preferably, the various embodiments showing different transmissionsequences for the four types of data occur in step 512 where navigationinformation is sent from service provider 108 to OBU 500.

Each of the various components or features disclosed can be used aloneor with other components or features. Each of the components or featurescan be considered discrete and independent building blocks. In somecases, combinations of the components or features can be considered adiscrete unit.

While various embodiments of the invention have been described, it willbe apparent to those of ordinary skill in the art that may moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents.

1. An on-board unit for receiving navigation information comprising: apower port configured to receive power from a power supply; a GPSantenna port configured to receive information from a GPS antenna; awireless communications port configured to receive information from awireless network; a display port configured to communicate with adisplay device; wherein the on-board unit receives navigationinformation through the wireless communications port; and wherein thenavigation information includes data formatted in relative coordinatesand data formatted in absolute coordinates.
 2. The on-board unitaccording to claim 1, wherein the navigation information includes firstmap regions encoded in relative coordinates and second map regionsencoded in absolute coordinates.
 3. The on-board unit according to claim1, wherein the navigation information includes first map featuresencoded in relative coordinates and second map features encoded inabsolute coordinates.
 4. The on-board unit according to claim 3, whereinthe first map features are roads.
 5. The on-board unit according toclaim 3, wherein the second map features are bodies of water.
 6. Theon-board unit according to claim 1, wherein the navigation informationincludes a first map feature encoded in relative coordinates and secondmap feature encoded in absolute coordinates.
 7. The on-board unitaccording to claim 6, wherein the first map feature is the same kind ofmap feature as the second map feature.
 8. The on-board unit according toclaim 1, wherein the navigation information includes a map feature,wherein a first portion of the map feature is encoded in relativecoordinates and second portion of the map feature is encoded in absolutecoordinates.
 9. The on-board unit according to claim 1, wherein thenavigation information includes a map feature, wherein a first axis ofthe map feature is encoded in relative coordinates and second axis ofthe map feature is encoded in absolute coordinates.
 10. A method forpreparing navigation information comprising the steps of: receiving arequest for navigation information; determining an overall route andconstructing an overall map; selecting a first portion of the overallmap; and determining whether the first portion is more efficientlyencoded using relative or absolute coordinates.
 11. The method accordingto claim 10, wherein the first portion is encoded using relativecoordinates.
 12. The method according to claim 11, further comprisingthe step of selecting a second portion of the overall map and encodingthe second portion using absolute coordinates.
 13. The method accordingto claim 12, further comprising the step of determining if the overallmap has been completely encoded.
 14. The method according to claim 12,further comprising the step of assembling the overall map using thefirst map portion and second map portion.
 15. The method according toclaim 10, wherein the first map portion is a geographical region. 16.The method according to claim 10, wherein the first map portion is a mapfeature.
 17. The method according to claim 12, wherein the first mapportion is a first geographical region and the second map portion is asecond geographical region.
 18. The method according to claim 12,wherein the first map portion is a map feature and the second mapportion is a second map feature.
 19. The method according to claim 12,wherein the first map portion is a first portion of a map feature andthe second map portion is a second portion of the map feature.
 20. Themethod according to claim 12, wherein the first map portion is a firstaxis of a map feature and the second map portion is a second axis of themap feature.
 21. A method for preparing navigation informationcomprising the steps of: receiving a request for the navigationinformation; preparing the navigation information using an absolutecoordinate system and a relative coordinate system; wherein the absolutecoordinate system uses two bytes to define each absolute coordinate; andwherein the relative coordinate system uses two bytes to define aninitial coordinate and uses one byte to define a subsequent coordinate.22. The method according to claim 20, wherein the subsequent coordinateis defined by a displacement from the initial coordinate.
 23. The methodaccording to claim 20, wherein the one byte used to define thesubsequent coordinate includes a value for displacement in a firstdirection.
 24. The method according to claim 23, wherein the one byteused to define the subsequent coordinate includes a value fordisplacement in a second direction.
 25. The method according to claim20, wherein the one byte includes a value for displacement in a firstdirection and a second direction.
 26. The method according to claim 25,wherein the first direction is in a direction of an X-axis and whereinthe second direction is in a direction of a Y-axis.
 25. The methodaccording to claim 20, wherein a first portion of bits of the one byteare used to define a value for displacement in a first direction. 26.The method according to claim 25, wherein a second portion of bits ofthe one byte are used to define a value for displacement in a seconddirection.
 27. The method according to claim 20, wherein the one byteincludes a first half comprising half of the bits of the one byte and asecond half of bits comprising the other half of bits of the one byte;wherein the first half of bits is used to define a value fordisplacement in a first direction and the second half of bits is used todefine a value for displacement in a second direction.